Filter element for a liquid-state process stream

ABSTRACT

A filter element assembly used to filter liquid-state process stream. The assembly includes first and second tubes. A ring is seated in one of the tubes. One or more filter elements extend from the ring into one of the tubes. The ring has a lip that extends beyond the outside of the tubes. Opposed open ends of the tube abut opposed surfaces of the ring lip. A seal surrounds the open ends of the tube and the ring lip. A clamp surrounds the seal. Liquid that flows between the ends of the tubes and the ring lip forces the seal against the clamp and the outer tubes to prevent the liquid from flowing beyond the seal.

RELATIONSHIP TO EARLIER FILED APPLICATION

[0001] This application is a divisional of U.S. patent application Ser.No. 9/499,017, filed Feb. 4, 2000, now abandoned.

FIELD OF THE INVENTION

[0002] This invention relates generally to a filter element forfiltering a liquid-state process stream.

BACKGROUND OF THE INVENTION

[0003] Filter assemblies are used in many industrial facilities toselectively remove material from liquid-state process streams. Filterassemblies are used to both remove undesirable contaminates from processstreams and to extract desirable filtrates out of process streams.

[0004] One type of filter assembly used in an industrial facility is abackwash filter assembly. This type of filter assembly typicallyincludes a number of filter element sub-assemblies that are connected atopposed ends to common inlet and outlet manifolds. Liquid to be filteredis introduced to the filter element sub-assemblies through the inletmanifolds. The filtered liquid is ported from the filter elementsub-assemblies through the outlet manifold. A flow diverter ispositioned inside the inlet manifold of this assembly. The flow diverteris able to selectively connect the inlet end of each filter elementsub-assembly to a drain line. A drive assembly, located outside of theinlet manifold, selectively moves the flow diverter between theindividual filter element sub-assemblies.

[0005] When the filter assembly is in use, the liquid to be filteredflows through filter elements internal to the filter assembly. Thematerial removed by the filter elements becomes trapped on the outersurfaces of the elements. Over time, a significant amount of trappedmaterial builds up on the filter elements. The build up of this materialeventually impedes the flow of liquid across the filter elements. Inother words, the build up of this material causes a relatively largepressure drop to develop across the filter elements. In order tomaintain the liquid flow through the filter elements at a reasonablerate, it is necessary to periodically remove the material that hasadhered to the filter elements. This material removal is accomplished bybackwashing the filter elements.

[0006] In backwashing, the flow diverter is set so as to establish afluid communication path between the filter element to be backwashed andthe drain line. A backwash liquid is flowed through the filter elementin the direction opposite the direction through which the liquid that isfiltered is flowed. Often, but not always, this backwash liquid is thefiltered liquid that has just been discharged from the outlet ends ofthe remaining filter elements. The backwash liquid forces the materialadhered to the side of the filter element off the filter element so thematerial flows down the drain. Often, a backwash filter system isoperated so that the flow diverter periodically couples each filterelement to the drain. By positioning the flow diverter in the inletmanifold, one filter element can be backwashed while the remainingfilter elements continue to perform their filter function. Thus, abackwash filter system can both simultaneously filter the liquid that isflowed to it for filtering and backwash one of its filter elements.

[0007] Two backwash filter systems are disclosed in the Applicant'sAssignee's U.S. Pat. Nos. 3,703,465 and 4,059,518.

[0008] While current backwash filter systems work reasonably well, thereare some limitations associated with their use. The flow diverter of atypical backwash filter system is often subjected to the force of thestream of liquid that is introduced into the inlet manifold forfiltering. The force of this liquid stream may cause the diverter toshift position. More particularly, the force of this fluid stream maycause unwanted rotational movement of the flow diverter when it isindexed from connection with one filter element to connection with asecond fluid element. Thus, the drive assemblies of available flowdiverters are typically provided with brake assemblies. These brakeassemblies precisely regulate the rotational movement of the flowdiverters to which they are attached. The need to provide this type ofbrake assembly typically adds to the cost of providing a backwash filtersystem.

[0009] Moreover, this type of brake assembly typically has at least twocomponents that bear against each other. Over time, these componentswear to the point at which they need to be replaced. Thus, the need tohave to maintain the brake assembly incorporated into a backwash filtersystem contributes to the overall cost of maintaining the system.

[0010] Moreover, many backwash filter systems are designed so that theflow diverter internal to the system tightly seals against the openingof the filter element sub-assembly against which it is aligned. In orderto maintain this seal, the flow diverter is typically pressed against anadjacent surface of the inlet manifold. This pressure typically resultsin the asymmetric loading of both the flow diverter and the sealslocated around the flow diverter. This asymmetric loading of thesecomponents, especially the seals, significantly accelerates the rate atwhich these components wear out and need to be replaced.

[0011] Still another disadvantage associated with backwash filtersystems, as well as other kinds of filter systems, concerns thesub-assemblies used to hold the filter elements in their complementaryhousings. This sub-assembly must, naturally, provide a liquid tightbarrier around the head end of the filter element with which it isassociated in order to foster the operation of the element. Secondly,this sub-assembly must allow the filter element to be removable from thehousing. Clearly, this is desirable so as to make it possible toreplace, clean or repair the filter element as needed. However, thesetwo objectives are, to a great extent, contradictory. Accordingly, thepresent sub-assemblies used to hold filter elements in their housingstend to be complex and/or expensive to provide.

SUMMARY OF THE INVENTION

[0012] This invention relates generally to a new and useful backwashfilter system. The backwash filter system of this invention includes aflow diverter subassembly that is both economical to provide andrelatively maintenance free to operate. The filter system of thisinvention also includes a coupling assembly for removably coupling afilter element into the complementary housing in which it is seated. Thecoupling assembly of this invention, in addition to providing therequisite liquid-tight barrier and allowing the filter element to beremoved, is economical to provide.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention is pointed out with particularity in the claims.The above and further features of this invention may be betterunderstood by reference to the following description taken inconjunction with the accompanying drawings, in which:

[0014]FIG. 1 is a side view of a backwash filter assembly of thisinvention;

[0015]FIG. 2 is a cross section view of the inside of the inlet manifoldof the assembly of this invention in which the components forming theflow diverter are depicted;

[0016]FIG. 3 is an exploded view of the filter assembly of thisinvention;

[0017]FIG. 4 is an enlarged cross sectional view of the flow diverter;

[0018]FIG. 5 is a perspective view of the outlet end of the sealintegral with the flow diverter;

[0019]FIG. 6 is a perspective view of the flow diverter drive assembly;

[0020]FIG. 7 is an exploded view of the components forming the driveassembly;

[0021]FIG. 8 is a cross sectional view of the filter element sealsub-assembly; and

[0022]FIG. 9 is a flow chart of the process steps through which theprogrammable logic controller cycles in order to regulate thebackwashing of the filter assembly.

DETAILED DESCRIPTION

[0023]FIGS. 1 and 2 depict the filter assembly 20 of this invention. Theassembly 20 includes an inlet pipe 22 through which the liquid to befiltered is introduced into the assembly. The outflow end of the inletpipe 22 is connected to a generally circularly-shaped closed inletmanifold 24. A number of filter element sub-assemblies 26 are connectedto the inlet manifold 24. Each sub-assembly 26 contains a filter element28

[0024] (FIG. 3) through which the liquid is flowed in order to remove amaterial from the flow stream. In the depicted version of the invention,filter assembly 20 includes eight filter sub-assemblies 26. In FIG. 1,two sub-assemblies 26 are not shown so that other components of thefilter assembly 20 can be illustrated. The outlet ends of filter elementsub-assemblies 26 are connected to a common outlet manifold 30. Outletmanifold 30 is a closed, circularly-shaped closed container locatedabove and axially aligned with inlet manifold 24. An elbow-shaped outletpipe 32 extends downwardly and outwardly away from the bottom of theoutlet manifold 30. The liquid filtered by the assembly 20 is dischargedfrom it through the outlet pipe 32. A frame 33, to which the inletmanifold 24 and pipe 32 are mounted, supports the rest of the assemblyabove ground level.

[0025] A flow diverter 34 is rotatably mounted in the inlet manifold 24.The flow diverter 34 is employed to selectively connect the inlet end ofeach filter element sub-assembly 26 to an elbow-shaped drain tube 36that is fitted in the base of the inlet manifold. A drain pipe 38 isconnected to the outlet end of the drain tube 36. Fluid flow downstreamof the drain pipe 38 is controlled by a pneumatically actuated valve 39in-line with the drain pipe. A drive assembly 40 located immediatelyabove the inlet manifold 24 controls the displacement of the flowdiverter 34. Whenever the flow diverter 34 is placed in registrationwith the inlet end of one of the filter element-sub assemblies 26, afraction of the filtered liquid discharged from the remainingsubassemblies 26 is flowed through the outlet manifold 30 to theselected sub-assembly. This fluid flow functions as a backwash flow thatforces caked filtrate off the outer surface of the filter element 28 ofthe selected subassembly 26. The backwash flow, including the removedfiltrate, is then flowed away from the filter assembly 20 through draintube 36 and drain pipe 38.

[0026] A differential pressure switch 42 is connected to the inlet andoutlet manifolds 24 and 30, respectively. The switch 42 receives apressure head from both manifolds 24 and 30 and outputs a signalwhenever the difference in pressures is above a select level. Aprogrammable logic controller 44 regulates both the opening and closingof drain pipe valve 39 and the actuation of the diverter drive assembly40. The programmable logic controller (PLC) 44 receives as an input thesignal generated by switch 42. While not illustrated, it should beunderstood that the programmable logic controller 44 also includes a keypad through which commands to manually override the controller'sregulation of the operation of the filter assembly 20 can be entered. Asdiscussed in more detail hereinafter, based on the differential pressurebetween the two manifolds 24 and 30, the time since the last backwashingand any manually entered commands, programmable logic controller 44actuates drive assembly 40 and open/closes valve 39 to facilitate thebackwashing of the filter elements 28.

[0027] With regard to valve 39, it should be understood that PLC 44regulates the flow of air to control members internal to the valve froma source 154. More particularly, PLC 44 regulates the state of valve 45which controls the air flow to valve 39.

[0028] The inlet manifold 24 has a circularly shaped shell 48. Theopposed ends of shell 48 are open. An end cap 50 with a rounded profileis welded or otherwise permanently secured to the open bottom end ofshell 48. Shell 48 is formed to have a circular inlet port 52. Inletport 52 is the opening into the manifold 34 to which inlet pipe 22 isconnected and through which liquid to be filtered is delivered into themanifold. The inlet manifold is further formed to a have a plurality ofoutlet ports 54 that are located in an arcuate, coplanar arrangementaround the manifold shell 48. In a gravity orientation, it will be notedthat outlet ports 54 are spaced below the space subtended by inlet port52. A tubular shaped discharge nipple 56 extends around each outlet port54. The discharge nipples 56 are welded or otherwise secured to theouter surface of shell 48 to extend away from the manifold 24.

[0029] The drain tube 36 is welded or otherwise permanently secured tothe manifold end cap 50 to extend a short distance into the bottom ofthe inlet manifold 24. A small piece of pipe, referred to as a receivingpipe 60, is fitted over and is permanently secured to the end of thedrain tube 36 that extends through the end cap 50.

[0030] The flow diverter 34, now described by reference to FIGS. 2-4, isa T-shaped section of pipe that is rotatably mounted in the exposed topend of receiving pipe 60. More particularly, the flow diverter 34 has aninlet section 62 that is horizontally aligned and outlet section 64 thatis vertically aligned. The flow diverter 34 is positioned in the inletmanifold 24 so that the outlet section is axially aligned with thelongitudinal axis of the manifold. The open end of the diverter outletsection 64 is seated in the open end of the receiving pipe 60. Moreparticularly, the open end of the diverter outlet section 64 is seatedin a bushing 66 that extends around the inner wall of the open end ofreceiving pipe 60. Bushing 66 is formed from a polytetraflourine(TEFLON®) resin with embedded glass so as to provide a low frictioninterface between the diverter 34 and the receiving pipe 60. The lowfriction interface facilitates the rotation of the diverter 34 relativeto the pipe 60. The bushing 60 does not, however, provide a liquid-tightseal between the flow diverter 34 and the receiving pipe 60. An annularflange 67 extends around diverter outlet section 64 at a location awayfrom the open end of the diverter. Flange 67 abuts an outer surface ofbushing 66.

[0031] Flow diverter 34 is shaped so that the open end of the inletsection 62 can be selectively placed in registration with any one of theoutlet ports 54 formed in the inlet manifold 24. Accordingly, it shouldbe understood that the diverter inlet section 62 is spacedlongitudinally away from the space subtended by inlet port 52, the spacethrough which liquid is flowed into the manifold 24. An annular seal 70,now described by reference to FIGS. 4 and 5, is fitted around the openend of diverter inlet section 62. Seal 70 is formed out of the samematerial from which bushing 66 is formed. It will be observed that theseal 70 is formed so that its front face 71 has a curved profile thatapproximates the curvature of the inner wall of the inlet manifold 24.The rear end of the seal 70 abuts a flange 72 that extends radiallyoutwardly and circumferentially surrounds the outer surface of themanifold inlet section 62. A set of springs 74 extend between theoutwardly facing surface of flange 72 and the seal 70. Moreparticularly, springs 74 are seated in small bores 75 formed in the rearend of the seal 70. The springs 74 urge the seal 70 outwardly so thatthe seal abuts the adjacent inner wall of the inlet manifold 24.

[0032] Seal 70 is further formed to have a lip 76 that extendsrearwardly from and circumferentially surrounds the outer perimeter ofthe rear face of the seal. The outer surface of lip 76 is flush with theadjacent outer surface of the rest of the seal 70. When the seal 70 isseated over the diverter inlet section 62, lip 76 extends over flange72. It will further be noted from FIG. 3, that flange 72 is shaped tohave two diametrically opposed tabs 78 that project away from the outerperimeter of the flange. The seal 70 is formed so that lip 76 definestwo diametrically opposed slots 80. When the seal 70 is fitted over theflow diverter 34, tabs 78 are seated in slots 80. Tabs 78 and slots 80thus cooperate to prevent the seal from rotating relative to thediverter inlet section 62.

[0033] An O-ring 82 extends between the outer surface of the diverterinlet section 62 and seal 70. The O-ring 82 is seated in a groove 84formed in the inner annular wall of the seal. The O-ring thus provides aliquid tight barrier between the seal 70 and the adjacent outer surfaceof the diverter inlet section. However, it should be understood thatseal 70 does not form liquid-tight barrier with the adjacent inner wallof the inlet manifold 24. Small volumes of liquid may flow in theinterstitial space between the front face 71 of the seal 70 and theadjacent inner wall of the inlet manifold 24.

[0034] A liquid-tight cap 86 is fitted over the end of the diverter 34opposite the outlet section 64. A drive rod 88 is integrally attached tothe top of the cap 86 and is axially aligned with the diverter outletsection 64. A drive shaft 98, which is part of the drive assembly 40, issecured to the end of drive rod 88. In the illustrated version of theinvention, a collar 89 mates the drive rod 88 and drive shaft 98together. A ring 87 is welded or otherwise permanently secured to theopen top end of manifold shell 48. A generally disk-shaped lid 90 issecured over the top of ring 87. Bolts 92 removably secure the lid 90 tothe ring 87. An O-ring 94 is disposed between the ring 87 and theadjacent surface of the lid 90 to provide a seal between these twocomponents. The O-ring 94 is seated in an annular groove 99 formed inthe open end face of the ring 87.

[0035] Lid 90 is formed so as to have a hollow boss 96 that extendsinwardly from the center of the lid. Drive shaft 98 extends into theinlet manifold through an opening in boss 96, (opening not identified).A set of V-seals 102 is fitted around drive shaft 98. The V-seals 102are seated in the recessed section of boss 96 that extends below therest of the lid 90. A packing ring 104 and a packing plate 108 that alsoextend around drive shaft 98 push the V-seals 102 outwardly so that theyform a liquid-tight barrier between the lid 90 and the drive shaft.Threaded fasteners 110 releasably hold the packing plate 108 against andto the lid 90.

[0036] The drive assembly 40 is now described by reference to FIGS. 6and 7. The drive assembly 40 includes a base plate 114 to which othercomponents of the assembly 40 are mounted. The base plate 114 is itselfmounted to a set of posts 116 that are integrally formed with lid 90 andthat extend upwardly from the surface of the lid. Fasteners (notillustrated) secure the base plate 114 to posts 116. Drive shaft 98extends through an opening 120 in base plate 114. A bushing 122 seatedin the outer perimeter of opening 120 provides a low friction interfacebetween drive shaft 98 and the base plate 114 so that the drive shaftcan freely rotate relative to the base plate.

[0037] A pair of spaced apart drive gears 122 is fixedly secured to thedrive shaft 98. Drive gears 122 are formed with teeth 126. The drivegears are formed so that teeth 126 are radially spaced 400 apart fromeach other. A top plate 128 is located over the drive gears 122. The topplate 128 is formed with an opening 130 through which the top end of thedrive shaft 98 extends. A second bushing 122 seated in opening 130provides a low friction interface between the drive shaft 98 and topplate 128. Bolts 132 and nuts 134 secure top plate 128 to base plate114. The bolts 132 extend through spacer tubes 136 that hold top plate128 away from base plate 114.

[0038] The drive gears 122 are rotated in step-wise pattern by apneumatic actuator 138. One end of actuator 138 is pivotally connectedbetween plates 114 and 128 by a pin 140. Pin 140 extends through tabs142 formed in the rear end of the actuator 138. Actuator 138 includes apiston rod 144 that is selectively extended out from and retracted backinto the actuator. A hexagonal shaped clevis 146 is secured over theexposed end of piston rod 144. A vertically aligned pin 148 extendsthrough an opening in the end of clevis 146 distal from the actuator138. The actuator 138 is mounted to plates 114 and 128 so that theclevis 146 is located adjacent the interstitial space between the drivegears 122. The pin 148 is positioned so that the opposed portions of thepin that extend out of the clevis abut the outer perimeters of the drivegears 122. Snap rings 149 hold pin 148 in a fixed position relative toclevis 146. A spring 150 extends between the clevis and one of the bolts132. More particularly spring 150 is secured to a clip 145 that isfitted to the bolt 132. The clip 145 is sandwiched between two spacertubes 143 that hold the clip between plates 122 and 128. Owing to itsposition, spring 150 holds clevis 146 so that pin 148 is held againstthe drive gears 122.

[0039] Piston rod 144 is extended out of and retracted back into theactuator 138 based on the selective application of pressurized air tothe actuator. This air comes from source 154 (FIG. 1) not part of thisinvention. A valve 156 controls the application of air from source 154to actuator 138 in order to extend and retract piston 144. Theprogrammable logic controller 44 sets the state of the valve 156.

[0040] A sub-assembly for monitoring the rotational position of the flowdiverter is located above top plate 128. Specifically a cam 160 isfitted to the portion of the drive shaft 98 that projects above the topplate 128. The cam 160 is formed with a rectangularly-shaped centeropening 162 to facilitate the fitting of the cam over a similarly shapedsection of the drive shaft 98. Thus, the cam 160 rotates in unison withthe rotation of the drive shaft 98. Cam 160 is further formed so as tohave an outer profile with a generally constant diameter profile. Thecam 160 is further formed to have, in its outer perimeter, anindentation 164.

[0041] A follower switch 166 is mounted to the top plate 128 to monitorthe rotational position of the cam 160. Bolts 168 secure the followerswitch 166 to the top plate 128. The follower switch 166 includes afollower member 170 that is biased outwardly and positioned to abut theouter perimeter of cam 160. The flow diverter 34 of the filter assembly20 of this invention has what is referred to as a “home” position. Thediverter is in this position when the diverter inlet section 64 isaligned with the arcuate section of the inlet manifold 64 subtended byand located below inlet port 52. When the flow diverter is in the homeposition it is not in registration with any of the outlet ports 54 towhich the filter element sub-assemblies 26 are connected. The filterassembly 20 is further constructed so that, when the flow diverter 34 isin the home position, cam 160 is positioned so that the cam indentation164 is in registration with switch follower member 170. Follower switch166 outputs a signal that indicates whether or not follower member 170is in registration with cam indentation 170. The signal generated by thefollower switch 166 is applied to the programmable logic controller 44.

[0042] A cover 172 is disposed over the base and top plates 114 and 128,respectively, of the drive assembly as well as the components mounted tothe plates. The head end of the drive shaft 98 extends through anopening 174 in the cover. A tubular bushing 175 provides a low frictioninterface between the drive shaft 98 and the cover 172. A pointer plate177 is mounted to the portion of the drive shaft 98 that extends out ofthe cover 172. Pointer plate 177 is fitted to the drive shaft 98 in amanner similar to which cam 160 is fitted to the drive shaft. Screw 176and washer 178 hold the pointer plate 177 to the drive shaft. Thepointer plate 177 is formed with a pointer 176 that provides a visualindication of the rotational position of the flow diverter.

[0043] The structure of a filter element sub-assembly 26 is nowdescribed by reference to FIGS. 3 and 8. Each sub-assembly 26 includes atubular shaped body 180. Body 180 has an elbow shaped inlet end 182 anda generally vertically aligned main section 184. A coupling member 186and an O-ring seal 188 sealing couple the open end of body inlet end 182to the open end of the associated discharge nipple 56. The filterelement 28 integral with each sub-assembly 26 is seated inside the bodymain section 184. An elbow tube 190 is fitted over the open end of bodymain section 184 and the filter element 28. The elbow tube 190 functionsas the flow path from body 180 into the outlet manifold 30.

[0044] The filter element 28 has a generally ring-shaped flange 194. Theflange is formed of material, typically metal, that will not corrodewhen exposed to the fluid stream being filtered. One or more filtermembers 196 are suspended from flange 194. The particular type of filterelement secured to the flange 194 is a function of the liquid that is tobe filtered and the material that is to be removed from the flow stream.For example, one such filter member 196 can be a single cylindricalmember formed from wire wrapped in a helical pattern around supportingstringers. The open top end of the filter member 196 is secured to anannular inner wall of the flange 194.

[0045] Alternatively, plural filter members may be secured to theflange. The flange of this type of filter element is formed to have asolid, disk shaped base. The filter members are sealingly secured toopenings formed in the flange base.

[0046] Filter element flange 194 is formed to have a generally constantdiameter outer wall 197. Flange 194 is dimensioned so that the outerwall 197 has a diameter slightly less than that of the adjacent innerwall of body main section 184 in which the filter member 196 is seated.An O-ring 198 is fitted in a groove 202 that extends inwardly from theouter wall 197 of the flange 194. Groove 202 and O-ring 198 arepositioned so that the O-ring abuts the inner wall of the body mainsection 184 below the open end of the body. Flange 194 is also formed tohave a lip 204 that extends circumferentially around and outwardly fromthe flange outer wall 197. The components of the filter elementsub-assembly 26 are further dimensioned so that lip 204 extends a shortdistance beyond the adjacent outer wall of body main section 184. Thus,when the filter element 28 is seated in the body 180, lip 204 seats overthe open end of the body. The lip 204 serves as the portion of theflange 194 from which the remaining components of the filter element 28are suspended.

[0047] The elbow tube 190 is seated over the end of the filter elementflange 194 that extends out of body 180. The end of the elbow tube thusseats against the face of flange lip 204 opposite the lip face seatedagainst body 180. A coupling assembly secures the body 180 and elbowtube 190 together, holds the filter element 26 in position and providesa seal around the outlet end of the filter element. The couplingassembly includes two coupling members 206. Each coupling member 206 hasa main body 208 that has a generally semicircular shape. Formedintegrally with each member main body 208 are inwardly directed,semi-circular ribs 210. One rib 210 is located around the top of themain body 208; the second rib 210 is located around the base of the mainbody.

[0048] When the coupling members 206 are fitted in position, the lowerrib 210 seats in a complementary annular groove 212 formed in the outerwall of the main body 180 a small distance below its open end. The upperrib 210 seats in an annular groove 214 formed in the outer wall of theelbow tube a small distance above the tube open end. Tabs 216 extendoutwardly from the opposed ends of the member main bodies 208. When thecoupling assembly 205 is assembled, fasteners 218 extend between thetabs 216 adjacent where the ends of the coupling members meet. Thecoupling assembly also includes a generally ring-shaped seal 220 formedof resilient material. Seal 220 is formed to define a void space 222that extends circumferentially around the seal. The seal 220 is furtherformed so that the inner portion thereof has two opposed lips 224. Thelips 224 are spaced apart from each other a small distance to provide anaccess therebetween into the void space 222. The lips 224 are shaped tohave coplanar outer surfaces 226 that collectively define the inner wallof the seal. Each lip has an angled surface 228 that partially definesthe void space 222. Each angled surface 228 extends diagonally away fromthe edge of the seal outer surface 226 with which the angled surface 228is associated.

[0049] The filter element 28, the body 180 and elbow tube of thesub-assembly 26 of this invention are assembled by first placing theseal 220 around the open end of the body 180. Filter element 28 is theninserted in the body 180. In the process of fitting the filter element28 in position, the flange lip 204 is seated against the open end of thebody 180. Also, seal 220 is positioned around flange lip 204 so that thelips abut the opposed face surfaces of the lip 204. Elbow tube 190 ispositioned over the portion of the flange 194 located above flange lip204. Thus, the outer surface 226 of a first one of the seal lips isseated against the outer wall of the body 180; the outer surface 226 ofthe second seal lip is seated against the outer wall of the elbow tube190.

[0050] Once the position of the elbow tube 190 and seal 220 are set,coupling members 206 are fitted in place. The inner surface of eachcoupling member is formed to define a curved groove 230 in which asemi-spherical portion of the seal 220 is seated. The fasteners 208clamp the coupling members 206 together.

[0051] Returning to FIG. 3, it can be seen that the outlet manifold 30is provided with a number of tube-shaped inlet nipples 234. A couplingmember 186 and an O-ring seal 188 sealing couple the discharge end ofeach elbow tube 190 to the inlet end of an associated one of the nipples234.

[0052] The filter assembly 20 of this invention is used by flowing theliquid to be filtered under pressure into the inlet manifold 24. As longas none of the filer elements 28 are not being backwashed, the valve 39is in the closed state. Liquid may flow into the flow diverter 34 anddrain pipe 36. After the flow diverter 34 and drain pipe 36 becomefilled with liquid, flow into these components stops. The liquid does,however, flow through the discharge nipples 56 into the filter elementsubassemblies 26. The liquid then flows through the filter members 196integral with the filter elements 26. During this part of the flowprocess, the material the filter element is intended to capture becomestrapped on the outer surface of the filter members 196. The filteredliquid flows into the center of the filter member 196 and, from there,out through the top of the element flange 194.

[0053] The liquid discharged from the filter element 28 is underpressure. Consequently, this liquid flows in the interstitial gapbetween the end face of elbow tube 190 and flange lip 204. The liquidthen flows into the seal void space 222 and through the interstitial gapbetween the flange lip 204 and the end face of element body 180.Continued flow of the liquid is, however, blocked by O-ring 198. Thus,eventually, the seal void space 222 fills with liquid. The liquidfilling the void space 222 causes the seal 220 to expand. The expansionof the seal urges the seal against the adjacent surfaces of the couplingmembers 206. The expansion of the seal 220 also urges the lower-locatedseal lip 224 against the outer surface of the assembly body 180; theupper-located seal lip 224 is urged against the outer surface of elbowtube 190. Thus, the expansion of the seal 220 causes the seal to form aliquid-tight barrier against the components against which it abuts.

[0054] The filtered liquid then flows from the filter elementsub-assemblies into the outlet manifold 30. The filtered liquid is thendischarged from the assembly through outlet pipe 32.

[0055] Over time, the outer surfaces of the filter members 196 becomecaked with the removed material. This material impedes the flow ofliquid across the filter members 196. In order to clean this materialoff the filter members, they are backwashed. The process steps throughwhich the filter assembly and more particularly, the programmable logiccontroller 44, cycles in order to backwash the filter members 196 is nowdescribed by reference to the flow chart of FIG. 9. Initially, theassembly, the programmable logic controller is actuated as representedby step 240. After actuation, the programmable logic controller 44monitors the signal generated by follower switch 166 to determinewhether or not the flow diverter 34 is in the home state, step 242. Thisdetermination is made because there is always a possibility that afterthe last actuation of the drive assembly 40, the flow diverter may notbe so positioned. This could happen if, for example, the drive assembly40 is manually shut off before all of the filter elements 28 have beenbackwashed.

[0056] If it is determined that the flow diverter is not in the homestate, programmable logic controller 44 attempts to reset the flowdiverter. As part of this process, the programmable logic controller 44determines how many times the flow diverter has been indexed, step 244.This step, step 244, may not be executed the first time the programmablelogic controller 44 cycles through the flow diverter resetting cycle.The programmable logic controller then indexes the flow diverter, step246. In this step, signals are set to valve 156 to regulate the flow ofpressurized air to actuator 138. Specifically, the actuator 138 ismanipulated so that piston rod 144 is first extended out of theactuator. This displacement of the piston rod 144 urges pin 148 againstthe drive gears 122. This movement forces the rotation of the drivegears 122, and through drive shaft 98 and drive rod 88, the likerotation of the flow diverter 34. Owing to the dimensioning of the drivegears 122 and the piston rod 144, each time the piston rod 144 isextended, the drive gears 122, and therefore the flow diverter 34, canonly be displaced a maximum of 40° . Once the piston rod 144 isextended, the programmable logic controller 44 resets valve 156 so as tocause the piston rod to retract back into the actuator 138.

[0057] It should also be understood that, in step 246, the value in afield indicating the number of times the flow diverter has been index inorder to return it to the home state is incremented by one. Prior to theinitial execution of the diverter resetting cycle, the count in thisfield will have been zeroed out.

[0058] After the flow diverter 34 is indexed, the programmable logiccontroller 44 again executes step 242 to determine if the flow diverternow is in the home state. If the flow diverter 34 is still not sopositioned, during the subsequent executions of the resetting cycle,step 244 is executed. Eventually, if the flow diverter 34 is not resetinto the home position the drive gears will rotate through a completecircle. In the described version of this invention, this occurs afterthe flow diverter is indexed nine times. Accordingly, if in step 244 itis determined that the flow diverter has been executed nine times theassembly is considered in a fault state, step 248. If the programmablelogic controller makes this determination, the controller 44 actuatesthe appropriate internal audio and visual alarms to provide personnel anindication of this condition.

[0059] Returning to step 242, it should be recognized that, in thisstep, the programmable logic controller 44 will more typically determinethat the flow diverter 34 is in the home position. When the flowdiverter is in this state, the assembly 20 can be used in a normalmanner. Programmable logic controller 44 then waits for a command toinitiate backwashing, step 252. In step 252, the backwash controlroutine in the programmable logic controller 44 waits to receive aninitiate backwash command based on one of three events occurring. First,the programmable logic controller is set to initiate backwashing if thesignal from switch 42 indicates that the fluid pressure in the outletmanifold 30 is below the pressure in the inlet manifold 24 by a setamount. This pressure drop serves as a primary indication that thefilter members have become clogged with removed material. Depending onthe liquid flowed through the assembly 20, this pressure is oftenbetween 7 and 25 psi. Alternatively, the programmable logic controller44 may automatically initiate backwashing if an internal timer indicatesthat a given period of time has elapsed since the filter elements werelast subjected to backwashing. The programmable logic controller 44 mayalso initiate backwashing if a command entered through the keypadindicates a system operator has determined that such backwashing isdesirable.

[0060] Once the backwash control routine receives an indication thatbackwashing should be initiated, the programmable logic controller 44proceeds to index the flow diverter from the home position to theadjacent outlet port 54 in the inlet manifold, step 254. As part of step254, a counter internal to the programmable logic controller 44 whichmaintains a count of how many times the flow diverter has been indexedis incremented. Prior to the first indexing of the flow diverter, thiscount is zeroed-out.

[0061] Then, the filter element 28 in communication with the outlet port54 is then backwashed, step 256. In step 256 valve 39 is opened to allowfluid flow through the drain tube 36 and drain pipe 38. Thus, once valve39 is opened, the pressure head of the fluid in the outlet manifold 30forces a fraction of the fluid in the outlet manifold 30 to flow in areverse direction to its normal pattern through the selected filterelement 28. This fluid flow forces the caked material off the outersurface of the filter member 196 integral with the filter element 28.The caked material and the backwash fluid flow out of the assembly 20through drain tube 36 and drain pipe 38.

[0062] It should be understood that, whenever valve 39 is open, a smallvolume of fluid might flow into the flow diverter through theinterstitial gap between the face of seal 70 and the inlet manifold 24.A small volume of liquid may also flow from the inlet manifold into thedrain tube 36 through gaps around bushing 66. These volumes of liquid,however, will not be a noticeable fraction of the liquid that is pumpedinto the assembly 20.

[0063] The programmable logic controller 44 is set to allow thebackwashing of a filter element 28 occur for a given amount of time.Typically this period is between 5 and 10 seconds. For some processstreams, the backwash period may approach one minute. Once thebackwashing of an individual filer element is completed, theprogrammable logic controller 44 closes valve 39.

[0064] Programmable logic controller 44 then, in step 258, determineshow many times the flow diverter has been indexed. This determination ismade in order to evaluate whether or not all the filter elements havebeen backwashed. In the described version of the invention, the flowdiverter is indexed eight times to be placed in registration with eachfilter element 28. If the flow diverter 34 has been indexed less thanthe requisite number of times, the programmable logic controller 44reexcutes steps 254, 256 and 258. In the reexecution of the indexingstep 254, the flow diverter 34 is advanced to the output port 54adjacent the outlet port with which it is currently in registration.

[0065] Eventually though, it is determined in step 258, that the flowdiverter 34 has been positioned against each of the outlet ports 54.Each of the filter elements 28 has thus been backwashed. The flowdiverter 34 is then indexed a final time, step 260, to return the flowdiverter to the home position.

[0066] After step 260 is executed, the programmable logic controller 44reexecutes step 242 in order to again determine whether or not the flowdiverter is in the home position. This determination is made to verifythat no malfunction occurred during the backwash process that would havecaused the flow diverter to fall out of alignment. If the flow diverter34 is properly aligned, the programmable logic controller 44 returns tostep 252 to await a command to initiate the backwashing process. If theflow diverter is not properly aligned, steps 244, 246 and 242 aresequentially reexecuted. These steps 244, 246 and 242 cyclicallyexecuted until the programmable logic controller determines that theflow diverter 34 is in the home position or the assembly is in the faultstate, step 250.

[0067] The filter assembly 20 of this invention is designed so that theflow diverter inlet section 64, the section of the flow diverter thatextends away from the longitudinal axis of the inlet manifold 24, isspaced away from the space subtended by manifold inlet port 52.Consequently, the fluid stream that flows into the manifold 24 throughport 52 does not subject the flow diverter 34 to appreciable sideloading. Since this side loading is substantially eliminated, driveassembly 40 is not provided with a complex braking system for preventingthe side-loading-induced rotation of the flow diverter 34. The omissionof the this type of braking system eliminates both the costs ofproviding it and the expenses associated with maintaining it.

[0068] Still another feature of the assembly 20 of this invention isthat the inlet section 64 is not placed in sealing contact with the endsof the associated outlet ports 54. Similarly, the discharge end of thediverter outlet section 64 is not sealed into the associated receivingpipe 60. An advantage of this arrangement is that it eliminates thecosts associated with having to provide liquid-tight barriers aroundthese interfaces and the need to have to maintain the integrity of thesebarriers.

[0069] Moreover, still another advantage of the filter assembly of thisinvention is that each filter element sub-assembly 26 is constructed sothat element O-ring 198 and the other components forming the couplingassembly collectively provide a liquid-tight barrier around thedischarge end of the filter element 28, and releasably secure the filterelement, body 180 and elbow tube 190 together. Collectively thesecomponents and element flange 194 are relatively economical to provide.

[0070] Accordingly, the filter assembly 20 of this invention offers anefficient way to filter liquid, while simultaneously backwashing one ofits filter elements 28, and that is economical to both construct andoperate.

[0071] Also, the programmable logic controller of the assembly 20 ofthis invention is designed to ensure that the flow diverter 34 isappropriately positioned during and after the backwashing process. Ifthe programmable logic controller cannot cause the return of the flowdiverter 34 to the appropriate position, the controller asserts an alarmso that operating personnel are made aware of the fault condition.

[0072] It should be understood that the foregoing description has beendirected to one particular version of the invention and that otherversions of the invention may vary from what has been described. Forexample, in one embodiment of the above versions of the invention, it isanticipated that the inlet pipe 22 and outlet pipe will have innerdiameters of approximately 8 inches and the inner diameter of the filterelement bodies will be, at its narrowest, approximately 4.2 inches. Inthis embodiment of the invention, the assembly 20 could filter materialflowing at a rate of up to 2000 gal./min. The system is also capable ofreceiving process flows at pressures up to 250 psi. When operating theassembly 20, it is further recommended that the pressure head of theprocess stream into manifold 24 be at least two times the level of thedifferential pressure that is sensed and used to trigger backwashing. Inother embodiments of the invention, the components may be of differentdimensions. In these alternative versions of the invention, thecharacteristics of the process streams flowed through the assembly 20will be different than those described above.

[0073] In the described version of the invention, the assembly 20 haseight separate filter element subassemblies 26. This is exemplary, otherversions of the invention may have more or less individual filterelement sub-assemblies 26.

[0074] It should further be clear that the invention may be assembledfrom components different from what has been described. For example, theinlet manifold 24, base 50, nipples 56 and ring 87 may be formed as asingle casting. Transducers other than the described switch 42 may beused to monitor the pressure in the manifolds 24 and 30 in order todetermine when the filter elements 28 should be subjected tobackwashing. Each manifold 24 and 30 may be provided with its ownpressure-sensitive transducer.

[0075] In the illustrated version of the assembly 20, flow diverter 34is constructed so that the inlet section 62 is located below the spacesubtended by inlet port 52. Not all versions of the invention may be soconfigured. In some versions of the invention, the inlet section 62 ofthe flow diverter, the section that extends radially away fromlongitudinal axis of the inlet manifold 24, may be located above thespace subtended by the inlet port 52. In these versions of theinvention, the only portion of the flow diverter exposed to the liquidstream discharged through the inlet port will be a circular,symmetrically shaped portion of the outlet section 64. Since the flowstream is exposed to a portion of the flow diverter that has a symmetricprofile, the flow stream will not subject the diverter to the sideloading that necessitates the fitting of a brake system to the driveassembly 40.

[0076] Furthermore, it should be noted that in the illustrated versionsof the invention, the home section of the inlet manifold shell 48, thesection that does not have any outlet ports, is the section of the shellthat is arcuately subtended by the inlet port 52. In other versions ofthe invention, this arcuate section of the shell 48 may be provided withoutlet ports 54; the home section of the shell would be partially orcompletely arcuately spaced from the section of the shell that definesthe inlet port 52.

[0077] Also, in the illustrated version of the invention, the outletmanifold 30 is shown located above the inlet manifold 24. Thisillustration should not be construed as limiting. In other versions ofthe invention, the components of the assembly 20 may have orientationsrelative to gravity and each other that are different from what has beendescribed.

[0078] Moreover, while a flow diverter 34 is shown mounted only in theinlet manifold 24 of the assembly 20, other versions of the inventionmay not be so limited. For example, in other versions of the invention,flow diverters may be mounted in both the inlet manifold 24 and theoutlet manifold 30. In these versions of the invention, the flowdiverter mounted in the outlet manifold would have an inlet sectionpositioned along the center axis of the manifold designed to receive abackwash liquid from a source external to the filter assembly. Theoutlet section of the flow diverter would be positioned to beselectively placed in registration with the inlet nipples 234. It shouldbe understood that, in these versions of the invention, the portion ofthe flow diverter that projects asymmetrically away from the rest of thediverter is typically positioned to be spaced away from an outlet portthrough which the filtered liquid is discharged.

[0079] These versions of the invention would be provided when it isdesirable to backwash the filter members 196 with a fluid other than theliquid the assembly is being used to filter. In these versions of theinvention, the backwash liquid is introduced into the filter element tobe backwashed through the flow diverter located in the outlet manifold30. In these versions of the invention, a single drive assembly 40 maybe employed to actuate both flow diverters. Alternatively, each flowdiverter may be provided with its own drive assembly. This latterembodiment of the invention may be useful when it is desirable toprovide a filter assembly of this invention that is capable ofbackwashing filter member 196 with either the filtered process liquid oran externally-supplied backwash liquid.

[0080] Also, it should be understood that the coupling assembly used toboth provide a liquid tight barrier around the filter element 28 andreleasably hold the filter element, the body 180 and elbow tube 190together may be used with other filter assemblies than the onedescribed. Moreover, it should be realized that in other versions of theinvention, the two tubes forming the outer components of the filterelement sub-assembly may have different shapes than what has been shown.Also, it may be desirable to place gaskets around the opposed annularfaces of flange lip 204. These gaskets would reduce the extent to whichliquid flows around these faces of the lip 204.

[0081] Accordingly, it is an object of the appended claims to cover allsuch modifications and variations that come within the true spirit andscope of the invention.

What is claimed is:
 1. A filter assembly comprising: an inlet manifold,said inlet manifold having a longitudinal axis and being formed todefine: an inlet port; a plurality of spaced apart outlet ports; and adrain outlet; a flow diverter rotating fitted in said inlet manifold,said flow diverter having an outlet section coupled to said manifolddrain outlet and an inlet section integral with and in contiguous fluidcommunication with said outlet section wherein, said inlet section ispositioned and shaped to be placed in selective communication with eachsaid manifold outlet port and said inlet manifold and said flow diverterare collectively configured so that said diverter inlet section isspaced away from space within said manifold subtended by the manifoldinlet port; a drive unit connected to said flow diverter for rotatingsaid flow diverter; a valve in fluid communication with the diverterdrain outlet for regulating fluid flow through the drain outlet; aplurality of filter element assemblies, each said filter elementassembly having a body with an inlet end and an outlet end and a filterelement disposed in said body and the inlet end of said body isconnected to one of the manifold outlet ports; an outlet manifold towhich the outlet ends of said filter element assembly bodies areconnected, said outlet manifold having a discharge port.
 2. The filterassembly of claim 1, wherein; said inlet manifold is formed withcircular outer wall; and said outer wall is shaped to define the inletport and the outlet ports wherein, the inlet port is positioned in saidouter wall to be longitudinally offset from said outlet ports.
 3. Thefilter assembly of claim 2, wherein said outer wall of said inletmanifold is shaped so that the outlet ports are centered around a commonpoint on the longitudinal axis of said inlet manifold.
 4. The filterassembly of claim 2, wherein said inlet manifold is shaped so that thedrain outlet is centered along the longitudinal axis of said inletmanifold and said flow diverter is mounted in said inlet manifold to becentered over and rotate around the longitudinal axis of said inletmanifold.
 5. The filter assembly of claim 2, wherein: said drain outletextends away from an end of said inlet manifold shell and said inletmanifold is formed so that said outlet ports are located between theinlet port and the end of said manifold from which said drain outletextends.
 6. The filter assembly of claim 2, further including acontroller for selectively actuating said power drive so that said powerdrive rotates said flow diverter so that the flow diverter inlet sectionis selectively indexed between a home position in which the inletsection is not in registration with any of the manifold outlet ports andbackwash positions in which the inlet section is in registration withthe manifold outlet ports and for opening/closing said valve, and saidcontroller is configured to: only open said valve when the flow diverterinlet section is in registration one of the manifold outlet ports; andto close said valve prior to actuating said drive unit to cause asubsequent indexing of said diverter outlet section.
 7. The filterassembly of claim 1, wherein: said inlet manifold is shaped so that theoutlet ports are arcuately disposed around said manifold and so that themanifold has a home section at which no outlet port is defined; saiddrive unit is configured so that each actuation of said drive unitresults the rotation of said flow diverter so that said diverter inletsection is indexed to be in registration with one of the manifold outletports or in registration with the manifold home position; and acontroller is provided for regulating actuation of said drive unit andfor opening/closing said valve and said controller is configured to:only open said valve after said drive unit is actuated to cause saiddiverter inlet section to be placed in registration with one of themanifold outlet ports; and to close said valve prior to actuating saiddrive unit to cause a subsequent indexing of said diverter inletsection.
 8. A filter system for filtering a liquid process stream, saidsystem including: an inlet manifold, said inlet manifold having acircular shell with a longitudinal axis, said shell being shaped todefine an inlet port and a plurality of outlet ports, wherein the outletports are formed in said shell to be longitudinally spaced away from theinlet port; a plurality of filter element assemblies, each said filterelement assembly having: a tube with an inlet end connected to one ofthe outlet ports of said inlet manifold and an outlet end distal fromthe inlet end; and a filter element disposed in said tube; an outletmanifold to which said outlet ends of said filter element assembly tubesare connected, said outlet manifold being formed with a discharge port;a flow diverter for directing fluid flow, said flow diverter beingrotatably fitted in said inlet manifold, said flow diverter being shapedto have an inlet section positioned to be selectively placed inregistration with each one of the manifold outlet ports and an outletsection integral said inlet section, said diverter outlet section beingcoupled to discharge fluid into a drain tube mounted to said inletmanifold that extends from said inlet manifold; a drive unit forrotating said flow diverter so as to index said diverter outlet sectionsbetween the outlet ports; and a valve in fluid communication with saidinlet manifold drain tube for regulating liquid flow through said draintube.
 9. The filter system of claim 8, wherein said inlet manifold has abase attached to a first end of said shell, said drain tube extends fromsaid base and said shell is formed so that the outlet ports are locatedin said shell so as to be between the inlet port and said base.
 10. Thefilter system of claim 8, wherein said inlet manifold shell is furtherformed to have a home section adjacent the outlet ports that is notprovided with an outlet port and said flow diverter is configured sothat said diverter inlet section is selectively positionable to be inregistration with the home section of said shell.
 11. The filter systemof claim 8, wherein: said inlet manifold is shaped so that the outletports are arcuately disposed around said manifold and so that themanifold has a home section at which no outlet port is defined; saiddrive unit is configured so that each actuation of said drive unitresults the rotation of said flow diverter so that said diverter outletsection is indexed to be in registration with one of the manifold outletports or in registration with the manifold home section; and acontroller is provided for regulating actuation of said drive unit andfor opening/closing said valve and said controller is configured to:only open said valve after said drive unit is actuated to cause saiddiverter outlet section to be placed in registration with one of themanifold outlet ports; and to close said valve prior to actuating saiddrive unit to cause a subsequent indexing of said diverter outletsection.
 12. A filter system for filtering liquid-state process streams,said filter system comprising: an inlet manifold, said inlet manifoldhaving: a shell with a longitudinal axis, said shell being shaped todefine and inlet port; a base over one end of said shell; a lid over asecond end of said shell; and a drain opening disposed in said base; aplurality of filter element assemblies, each said filter elementassembly having: a body with first and second ends, the first end ofsaid body being attached to said inlet manifold so that said body is influid communication with said inlet manifold; and a filter elementdisposed in said body, wherein the first ends of said filter elementbodies are attached to said inlet manifold shell at locations that arelongitudinally spaced from the space in said manifold subtended by saidmanifold inlet port; an outlet manifold to which said second ends ofsaid filter element assembly bodies are attached, said outlet manifoldbeing shaped to have a discharge port; a flow diverter disposed in saidinlet manifold, said flow diverter having an inlet section, said inletsection being positioned to be selectively placed in fluid communicationwith each said filter element assembly and an outlet section contiguouswith said inlet section, said outlet section being rotatably mounted inand in fluid communication with the inlet manifold drain opening; adrive unit for displacing said flow diverter to index said flow diverteroutlet section between said filter element assemblies; and a valve forregulating fluid flow from the manifold drain opening.
 13. The filtersystem of claim 12, wherein said filter element assemblies extendforward from said inlet manifold towards said outlet manifold and saidshell is formed so that the inlet port is located between said lid and alongitudinal location of said shell at which said filter elementassembly bodies are attached to said shell.
 14. The filter system ofclaim 12, wherein said inlet manifold shell is further formed to have ahome section adjacent the outlet ports that is not provided with anoutlet port and said flow diverter is configured so that said diverterinlet section is selectively positionable to be in registration with thehome section of said shell.
 15. The filter system of claim 14, whereinsaid inlet manifold shell is shaped so that the home section is locatedwithin an arcuate section of said shell subtended by the inlet port. 16.The filter system of claim 12, wherein: said inlet manifold is shaped sothat the outlet ports are arcuately disposed around said manifold and sothat the manifold has a home section at which no outlet port is defined;said drive unit is configured so that each actuation of said drive unitresults the rotation of said flow diverter so that said diverter outletsection is indexed to be in registration with one of the manifold outletports or in registration with the manifold home position; and acontroller is provided for regulating actuation of said drive unit andfor opening/closing said valve and said controller is configured to:only open said valve after said drive unit is actuated to cause saiddiverter outlet section to be placed in registration with one of themanifold outlet ports; and to close said valve prior to actuating saiddrive unit to cause a subsequent indexing of said diverter outletsection.
 17. A filter element assembly, said assembly including: a firsttube, said first tube having an outer diameter, an inner diameter and anopen end; a filter unit, said filter unit including: a flange, saidflange having a body with an outer surface wherein said body isdimensioned to be fitted in said open end of said first tube and a lipthat extends radially away from the outer surface of said flange body,said lip having an outer diameter that is greater than the outerdiameter of said first tube so that when said flange body is disposed insaid first tube, said lip seats around the open end of said first tube;at least one filter member attached to said flange, said filter memberhaving an open end adjacent said flange body; and a filter unit sealthat extends between said flange body and an inner wall of said firsttube for establishing a barrier between said first tube and said flange;a second tube, said second tube having an open end, said second tubebeing positioned so that the open end of said second tube is seated oversaid flange lip; and a clamp assembly, said clamp assembly including: acoupling unit, said coupling unit having a first and second spaced apartannular, inwardly extending ribs, said coupling unit being fitted aroundsaid first and second tubes so that the first said rib bears againstsaid first tube and the second said rib bears against said second tube;and an annular seal located between said ribs of said coupling unit,said seal extending around said first tube, said flange lip and saidsecond tube, said seal being shaped to have an annular void spacewherein said flange lip is seated in the void space.
 18. The filterelement assembly of claim 17, wherein said coupling unit is formed froma plurality of arcuately shaped coupling members.
 19. The filter elementassembly of claim 17, wherein said coupling unit has an inner wall thatdefines an annular groove and said clamp assembly seal is seated in thegroove.
 20. The filter element assembly of claim 17, wherein said filtermember extends from said flange so as to extend into said first tube.21. The filter element assembly of claim 17, wherein said filter memberis a single member that extends from said flange so as to extend intosaid first tube.
 22. The filter element assembly of claim 17, whereinsaid clamp assembly seal is formed so that the seal void space in whichsaid flange lip is seated is larger than the portion of said flange lipseated in the void space and said clamp assembly seal is further formedto have a first annular lip that extends around a section of said firsttube against which said flange lip is seated and a second lip thatextends around a section of said second tube adjacent said flange lipand each said annular lip defines a portion of the clamp assembly sealvoid space.
 23. The filter element assembly of claim 22, where saidclamp assembly seal is further formed so that each said annular lipabuts a portion of said flange lip.
 24. The filter element assembly ofclaim 17, wherein said flange is formed so that a portion of said flangebody extends beyond said lip into said second tube.
 25. The filterelement assembly of claim 17, wherein a portion of said flange body thatis disposed in said first tube is formed with a groove and said filterunit seal is fitted in the groove formed in said flange body.
 26. Afilter element assembly, said filter element assembly including: firstand second tubes, each said tube including an outer wall and an openend; a filter unit, said filter unit comprising: a ring, said ring atleast partially disposed in the open end of said first tube and having alip that is dimensioned to extend to at least the outer walls of saidtubes, wherein said first and second tubes are positioned so that theopen ends of said tubes abut said lip; and a filter member attached tosaid ring and positioned to extend into said first tube; a first sealdisposed between said ring and the inner wall of said first tube; asecond seal disposed around the open end of said first tube, said ringlip and the open end of said second tube, said second seal having aninwardly directed opening wherein said flange lip is seated in theopening; and a clamp, said clamp having a body that surrounds saidsecond lip, a first rib that extends from said clamp body that engagessaid first tube and a second rib that extends from said clamp body thatengages said second tube.
 27. The filter element assembly of claim 26,wherein said clamp is formed from a plurality of arcuately shapedcoupling members.
 28. The filter element assembly of claim 26, whereinsaid filter member is a single member that extends from said ring. 29.The filter element assembly of claim 17, wherein said second seal isformed so that the opening in which said ring lip is seated is largerthan the portion of said ring lip seated in the opening and said secondseal is further formed to have a first annular lip that extends around asection of said first tube that abuts said ring lip and a second lipthat extends around a section of said second tube that abuts said ringlip and each said annular lip defines a portion of the second sealopening.
 30. The filter element assembly of claim 29, where said secondseal is further formed so that each said annular lip abuts a portion ofsaid ring lip.
 31. The filter element assembly of claim 26, wherein saidring is shaped to have a section that extends beyond said lip into saidsecond tube.
 32. The filter element assembly of claim 17, wherein aportion of said ring that is disposed in said first tube is formed witha groove and said first seal is fitted in the groove formed in saidflange body.
 33. A filter element assembly, said filter element assemblyincluding: first and second tubes, each said tube including an outerwall and an open end; a filter unit, said filter unit including: aflange, said flange at least partially disposed in the open end of saidfirst tube and having a lip that is dimensioned to extend beyond theouter walls of said tubes, wherein said first and second tubes arepositioned so that the open ends of said tubes abut said lip; and afilter member attached to said flange and positioned to extend into saidfirst tube; a first seal disposed around the open end of said firsttube, said flange lip and the open end of said second tube, said firstseal shaped to define an opening in which the section of said flange lipthat extends beyond the outer walls of said tubes are seated, theopening being larger than the section of said flange lip seated therein,a first lip disposed against the open end of said first tube and asecond lip disposed against the open end of said second tube and saidseal lips at least partially define the opening in said first seal; anda clamp, said clamp having a body that surrounds said first lip, a firstrib that extends from said clamp body that engages said first tube and asecond rib that extends from said clamp body that engages said secondtube.
 34. The filter element assembly of claim 33, wherein said clamp isformed from a plurality of arcuately shaped coupling members.
 35. Thefilter element assembly of claim 33, wherein said clamp body is formedwith an inwardly directed groove and said first seal is seated in thegroove.
 36. The filter element assembly of claim 33 wherein said filtermember is a single member that extends from said flange.
 37. The filterelement assembly of claim 33, where said first seal is further formed sothat each said annular lip abuts a portion of said flange lip.
 38. Thefilter element assembly of claim 33, wherein said flange is formed sothat a portion of said flange extends beyond said lip into said secondtube.
 39. The filter element assembly of claim 33, further including asecond seal extending between a portion of said flange disposed in saidfirst tube and said first tube.